Karl Filipsson, Eva Bergman, Larry Greenberg, Martin Österling, Johan Watz and Ann Erlandsson recently published the paper “Temperature and predator-mediated regulation of plasma cortisol and brain gene expression in juvenile brown trout (Salmo trutta)” in the journal Frontiers in Zoology.

In this study, we tested how temperature and the presence of a cold-water adapted predatory fish (burbot, Lota lota) affected primary stress responses (i.e. cortisol and mRNA levels of stress-related genes) in juvenile brown trout (Salmo trutta). We found that trout had elevated cortisol levels in the presence of burbot, and that stress-related gene expressions varied a lot with temperature. In addition, we found that the predator-induced effects on mRNA levels were temperature dependent for some of the genes. This, together with the directly temperature-mediated effects that we observed in our study, suggest that warming winters can have major impact on primary stress responses in overwintering salmonids, for instance in encounters with predators.

In the abstract of the paper, we wrote that:

“Temperature affects many aspects of performance in poikilotherms, including how prey respond when encountering predators. Studies of anti-predator responses in fish mainly have focused on behaviour, whereas physiological responses regulated through the hypothalamic-pituitary-interrenal axis have received little attention. We examined plasma cortisol and mRNA levels of stress-related genes in juvenile brown trout (Salmo trutta) at 3 and 8 °C in the presence and absence of a piscivorous fish (burbot, Lota lota).

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A redundancy analysis revealed that both water temperature and the presence of the predator explained a significant amount of the observed variation in cortisol and mRNA levels (11.4 and 2.8%, respectively). Trout had higher cortisol levels in the presence than in the absence of the predator. Analyses of individual gene expressions revealed that trout had significantly higher mRNA levels for 11 of the 16 examined genes at 3 than at 8 °C, and for one gene (retinol-binding protein 1), mRNA levels were higher in the presence than in the absence of the predator. Moreover, we found interaction effects between temperature and predator presence for two genes that code for serotonin and glucocorticoid receptors.

Our results suggest that piscivorous fish elicit primary stress responses in juvenile salmonids and that some of these responses may be temperature dependent. In addition, this study emphasizes the strong temperature dependence of primary stress responses in poikilotherms, with possible implications for a warming climate.”

You can read the paper for free on the journal website, as the paper is published open access through funding provided by Karlstad University.

On Tuesday 25 February, Kalle Filipsson, RivEM PhD student, will give a seminar entitled ”From behaviour to genes: anti-predator responses of brown trout under winter conditions”. The seminar starts at 13.15 in room 5F416, everyone who wants to is welcome to attend the seminar.

This seminar is a practice seminar in preparation for Kalle’s (my) licentiate defense, which will be held Friday 13 March at 10:00. More information about the licentiate seminar will be provided closer to the defense.

On Tuesday October 9, two seminars will be held at the biology department at Karlstad University.

Adaptive potential and evolutionary responses to climate change: Arctic char and threespine stickleback in Greenland – Michael Hansen, Professor, Aarhus University

Ecological genetics – What’s it about and how can we use it? – Karl Filipsson, NRRV PhD-student, Karlstad University

The seminars will be held in room 5F416 and start at 13:15. Everyone who wants to are welcome to attend the seminars.

In April 2018, Anissa Bengattat from France visited Karlstad University and did an internship with NRRV. Here she writes about her weeks in Sweden.

Hej där!

I’m Anissa Bengattat, a French student in HND ‘Management and Protection of Nature’ in a town located in France, named Vic-en-Bigorre. As a practical training, I have been doing my three-weeks internship at Karlstad University with the Ecology and Conservation Biology program.           

During these weeks, I have learned vastly about different aspects of  freshwater ecology.  My main mission has been to collect, sort, identify and archive macro-invertebrates, collected in the field, in the freshwater stream Rannån. With the help of Richard Durtsche, guest-professor from the USA, and his student Rachel Prokopius, I managed to follow a project from the start to the end.

I have tested digital imaging of the identified invertebrates, and I have seen the calorimetry process, used in order to make links with the fishes‘ energetics consumption.

 I have also been in the stream aquarium laboratory to participate in some interesting experiments. First, I have learned about the whole fishes respirometry system, made up by R. Durtsche, where we studied oxygen consumption for brown trout. Then, I’ve learned about Karl Filipsson’s experiments about climate change effects on predation on brown trout. Their behaviour, linked to the temperature and the presence or not of burbot, and how to identify it scientifically by extracting trouts‘ RNA.

 Finally, I have attended master classes for these three last weeks, which consolidated my idea to do a bachelor after my HND, and then a master, if possible, abroad.

This internship wasn’t only about studies to me, it was also about meeting new people in another country with a different way of living, and a different way of teaching. It was about making concrete links in my mind between how much I still have to learn, and how to develop into an accomplished scientist.

Thanks to John Piccolo who set up my internship, thanks to the international office of Karlstad university which helped, and thanks to Elio Bottagisio, the French master student who told me about this program. And finally, thanks to all the people who taught me things during this internship,  Richard Durtsche, Rachel Prokopius, Olle Calles, and Karl Filipsson. I hope to come back.

On Tuesday 3 April 2018, Karl Filipsson, PhD student at Karlstad University, will give a talk titled “The effects of temperature and light conditions during winter on antipredator responses of juvenile brown trout against burbot”. The seminar will start at 13:15 in room 5F416 at Karlstad University. Everyone is welcome to attend the seminar.

Karl Filipsson has recently joined the NRRV-research group. Here he writes about his previous work and what he intends to do as a PhD-student at Karlstad University:

My name is Karl Filipsson and I recently started my PhD in the River Ecology and Management Research Group (NRRV) at Karlstad University, where I am going to study the winter ecology of stream fishes in relation to climate change. I have a master’s degree in biology from the University of Gothenburg, with focus on aquatic and evolutionary ecology. Although I have a broad interest in fish ecology and behavior, I have developed a special interest for fish inhabiting streams. In my master project I studied the effect of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae on brown trout (Salmo trutta). The project mainly examined behavioral responses in the host fish, but growth and cardiorespiratory parameters were measured as well.

In my PhD I will use an experimental approach to look at the consequences of warmer winters on predator-prey interactions and early life-history performance in stream fishes. I will use brown trout and burbot (Lota lota) as model species. River ecosystems and associated fish populations have a significant role in providing important ecosystem services. Therefore, it is of great importance to acquire knowledge on the winter ecology of stream fishes under climate change. Hopefully, results from this project will not only elucidate how stream fishes are adapted to winter conditions and respond to environmental change, but will also provide information for stakeholders and decision makers on how to manage fish populations and stream ecosystems in a future influenced by global climate change.

In addition to research, I have a great interest in scientific outreach. I have previously been working at the science center Universeum in Gothenburg and as scuba diving guide, and I am very keen on taking on the challenge to communicate research to the broader public and to be teaching in higher education.”

Some of Karls previous work on the interaction between juvenile brown trout and frehswater pearl mussel larvae is published in the scientific articles Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta) and Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.).